The Li-mediated ammonia synthesis (LiMeAS) is currently the only proven way to synthesize ammonia electrochemically. However, the exact mechanism is not fully understood, with recent publications stating that the elusive solid electrolyte interface (SEI) layer could be a very important factor. Similar to the battery literature, it is believed to prevent excess electrolyte decomposition and regulate the Li plating behavior. In the case of the LiMeAS the SEI layer may control the diffusion rate of the reactants, N2, H+ and Li+. In this proposal, we aim to fundamentally understand the SEI layer as well as the deposit of the electrode at different reaction conditions (electrolyte solvents, salts, current densities and pressures) and investigate how these changes influence the faradaic efficiency (FE). The expected results will help to further understand and improve the performance of the LiMeAs and bring us a step closer to a renewable ammonia production.